Abstract: Targeting the high-resolution mass spectrometric detection requirements for thermal ions at the heliospheric boundary, a high-resolution Time-Of-Flight (TOF) system was designed. This system utilized a linear reflection electric field formed by reflective wire-generated parallel electrodes to reflect incident ions once, thereby extending ion flight time and shortening time-of-flight peak broadening without increasing sensor size, thus achieving the goal of enhancing the mass resolution of the TOF system. Simulations were conducted on electrode electric field distribution and typical particle trajectories within the sensor, and simulation analyses of mass resolution capability were performed for typical heliospheric boundary thermal ion components. Simulation results demonstrate that the mass resolution of this high-resolution TOF system for heliospheric boundary thermal ions is ≥50, meeting the requirements for high-resolution mass spectrometric detection of thermal ions in deep space, especially at the heliospheric boundary.